Interface Level

Parameters

Attach type. Possible values are DDI_ATTACH and DDI_RESUME. Other values are reserved. The driver must return DDI_FAILURE if reserved values are passed to it.

Description

The attach(9E) function is the device-specific initialization entry point. This entry point
is required and must be written.

DDI_ATTACH

The DDI_ATTACH command must be provided in the attach(9E) entry point. DDI_ATTACH
is used to initialize a given device instance. When attach(9E) is called
with cmd set to DDI_ATTACH, all normal kernel services (such as kmem_alloc(9F))
are available for use by the driver. Device interrupts are not blocked when
attaching a device to the system.

The attach(9E) function is called once for each instance of the device
on the system with cmd set to DDI_ATTACH. Until attach(9E) succeeds, the
only driver entry point which may be called is getinfo(9E). See the
Writing Device Drivers for more information. The instance number may be obtained using ddi_get_instance(9F).

At attach time, all components of a power-manageable device are assumed to
be at unknown levels. Before using the device, the driver needs to
bring the required component(s) to a known power level. The pm_raise_power(9F) function
can be used to set the power level of a component. This
function must not be called before data structures referenced in power(9E) have been
initialized.

DDI_RESUME

The attach() function may be called with cmd set to DDI_RESUME after
detach(9E) has been successfully called with cmd set to DDI_SUSPEND.

When called with cmd set to DDI_RESUME, attach() must restore the hardware
state of a device (power may have been removed from the device),
allow pending requests to continue, and service new requests. In this case, the
driver must not make any assumptions about the state of the hardware,
but must restore the state of the device except for the power
level of components.

If the device driver uses the automatic device Power Management interfaces (driver
exports the pm-components(9P) property), the Power Management framework sets its notion of the
power level of each component of a device to unknown while processing
a DDI_RESUME command.

The driver can deal with components during DDI_RESUME in one of the
following ways:

If the driver can determine the power level of the component without having to power it up (for example, by calling ddi_peek(9F) or some other device-specific method) then it should notify the power level to the framework by calling pm_power_has_changed(9F).

The driver must also set its own notion of the power level of the component to unknown. The system will consider the component idle or busy based on the most recent call to pm_idle_component(9F) or pm_busy_component(9F) for that component. If the component is idle for sufficient time, the framework will call into the driver's power(9E) entry point to turn the component off. If the driver needs to access the device, then it must call pm_raise_power(9F) to bring the component up to the level needed for the device access to succeed. The driver must honor any request to set the power level of the component, since it cannot make any assumption about what power level the component has (or it should have called pm_power_has_changed(9F) as outlined above). As a special case of this, the driver may bring the component to a known state because it wants to perform an operation on the device as part of its DDI_RESUME processing (such as loading firmware so that it can detect hot-plug events).